Mechanical particle coating using ethylcellulose nanoparticle agglomerates for preparing controlled release fine particles; effect of coating temperature on coating performance

Preparation of sustained-release tablets using a solventless-mixing tablet coating technique: Particle design of dry ammonioalkyl methacrylate copolymer latex with high coating performance using sodium lauryl sulfate

The aim of this study was to produce sustained-release tablets by V-shaped blending of polymer and tablets without using solvents or heating, and we investigated the design of polymer particles with high coating performance by modifying the structure of the particles using sodium lauryl sulfate. Dry-latex particles of ammonioalkyl methacrylate copolymer were prepared by adding the surfactant into aqueous latex, followed by freeze drying. The resulting dry latex was mixed with tablets (1:10) using a blender and the resulting coated tablets were characterized. Tablet coating by the dry latex was promoted as the weight ratio of surfactant to polymer increased. At a surfactant ratio of 5%, deposition of the dry latex was most effective and the resulting coated tablets (annealed at 60 °C/75%RH for 6 h) exhibited sustained-release characteristics over a period of 2 h. The addition of SLS prevented coagulation of colloidal polymer in the freeze drying, resulting in a loose-structured dry latex. This latex was easily pulverized by V-shaped blending with tablets and the resulting fine particles with high adhesiveness were deposited on the tablets. However, at a surfactant ratio of 10%, the coating of dry latex decreased due to reduced adhesiveness.

Design and preparation of nanocomposite acrylate coating agents for binder-free dry coating of 100 µm-sized drug-containing particles and their coating performance

For binder-free dry particulate coating to prepare controlled-release micron-sized particles, we designed nanocomposite coating agents with the intention to form a core-shell structure composed of two types of acrylic polymers with different glass transition temperatures (Tg) and evaluated their coating performance. A series of nanocomposite acrylic latexes synthesized by emulsion polymerization was freeze-dried after salting-out to create the powder form. An ion-exchange resin loaded with diclofenac sodium (DS, a model drug) (IER-DS) with a median diameter of approximately 100 µm was used as the core particle. Dry coating of the IER-DS with nanocomposite coating agents was carried out using a laboratory-made coating apparatus assisted with mild-intensity vibration and zirconia bead impaction. The coated particles were cured by heating at a temperature 20 °C higher than the Tg for 12 h to complete the film-forming process. It was found that the highest coating efficiency (more than 70%) and a remarkably prolonged release period of the drug (the time required for 50% release reached approximately 12 h) could be achieved when nanocomposite coating agents with a soft polymeric core (Tg = 30 °C) and a hard polymeric shell (Tg = 80 °C) were applied. In contrast, nanocomposite coating agents with a combination of a hard polymeric core and a soft polymeric shell resulted in lower coating efficiency. These results demonstrate that nanocomposite polymeric coating agents composed of a soft core and hard shell are effective for the production of drug-loaded microparticles with a prolonged release function by a binder-free dry-coating process.

Polymers and Nanoparticles for Statin Delivery: Current Use and Future Perspectives in Cardiovascular Disease

Atherosclerosis-related coronary artery disease (CAD) is one of the leading sources of mortality and morbidity in the world. Primary and secondary prevention appear crucial to reduce CAD-related complications. In this scenario, statin treatment was shown to be clinically effective in the reduction of adverse events, but systemic administration provides suboptimal results. As an attempt to improve bioavailability and effectiveness, polymers and nanoparticles for statin delivery were recently investigated. Polymers and nanoparticles can help statin delivery and their effects by increasing oral bioavailability or enhancing target-specific interaction, leading to reduced vascular endothelial dysfunction, reduced intimal hyperplasia, reduced ischemia-reperfusion injury, increased cardiac regeneration, positive remodeling in the extracellular matrix, reduced neointimal growth and increased re-endothelization. Moreover, some innovative aspects described in other cardiovascular fields could be translated into the CAD scenario. Recent preclinical studies are underlining the effect of statins in the stimulation and differentiation of endogenous cardiac stem cells, as well as in targeting of local adverse conditions implicated in atherosclerosis, and statin delivery through poly-lactic-co-glycolic acid (PLGA) appears the most promising aspect of current research to enhance drug activity. The present review intends to summarize the current evidence about polymers and nanoparticles for statin delivery in the field of cardiovascular disease, trying to shed light on this topic and identify new avenues for future studies.

Enhancement of atorvastatin oral bioavailability via encapsulation in polymeric nanoparticles

Despite the fact that atrovastatin (At) is being one of the bestselling statins used to prevent complicated cardiovascular diseases, its low oral bioavailability decreases its clinical relevance. Herein, incorporation of At into ethylcellulose nanoparticles (At-NPs) was executed to test if it would enhance its oral bioavailability. The emulsification-evaporation method was used to prepare the At-NPs. The prepared nanoparticles were characterized by measuring the particle size, zeta potential as well as using FTIR, DSC, and XRD examination. The entrapment efficiency, drug content, and the in vitro release behavior of At-NPs were also examined. The in vivo oral bioavailability of the selected At-NPs formula was tested after being given orally to New Zealand rabbits. The nanoparticles obtained had a high drug content and a distinct spherical shape but with varying sizes. No physical or chemical interactions were detected between At and the nanoparticles as confirmed by FTIR, DSC, and XRD. The in vitro release study of At from the prepared At-NPs has shown nanoparticles size-dependent release behavior. The in vivo oral absorption testing confirmed the bioavailability of the prepared At-NPs to be as follows: (C_max = 940 ng/ml and AUC_0-12 = 8759 ng.h/ml) > Lipitor® (C_max = 635 ng/ml and AUC_0-12 = 4367 ng.h/ml) > At (C_max = 515 ng/ml and AUC_0-12 = 2517 ng.h/ml). These results revealed that the oral formula of At-NPs increases the bioavailability of At 3.87 times. This makes ethylcellulose nanoparticles an esteemed candidate nano-vehicle for At, increasing its bioavailability and thus improving its clinical relevance.